It makes a difference if its clumping litter. Clumping litter you could just choke down the clumps without tasting them. But non-clumping you'd have to taste more cat pee.

There's nothing here that indicates the litter box has been used yet. Whereas if a diaper has contents, it's probably been used.

It could just be the lining of the diaper, or whatever.

I think that with a diaper, there's simply less volume of potential material to ingest, making it the favourable option.